Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$194.40	3.269%	$200.7549	$200.75	$200.75	$200.80
Purchase #2	$118.87	11.190%	$132.1716	$132.17	$132.15	$132.20
Purchase #3	$150.78	3.854%	$156.5911	$156.59	$156.60	$156.60
Purchase #4	$59.80	8.597%	$64.941	$64.94	$64.95	$64.90
Purchase #5	$171.40	5.433%	$180.7122	$180.71	$180.70	$180.70
Purchase #6	$126.26	12.536%	$142.088	$142.09	$142.10	$142.10
Purchase #7	$132.56	5.473%	$139.815	$139.82	$139.80	$139.80
7 purchase totals =	$954.07		$1,017.0738	$1,017.07	$1,017.05	$1,017.10